Potato treating process



2 Shams-Smet l F. mm OT'I'OI TREATNG PROCESS Filed June 19, 1943substantially prevent Patented Mar. 25 1941 2,417,932 PorA'ro TREATINGritocnss i AArthur- F. Kalmar,

- Food Machinery Riverside, Calif., assignor to Corporation,

San Jose, Calif.,

a corporation of Delaware Application June 19, 1943, Serial No.'491,521

(C1. 99me) Claims.

This invention has to do with the treatment of fruit and vegetables forthe prevention of decay and for improving the appearance of these.Although adapted to be employed in treating other fruits and vegetables,it is especially useful in the treatment of potatoes.

It is a broad object of this invention to provide a process of treatingpotatoes and particularly White Rose potatoes, so as to improve theappearance of the potatoes and lessen the decay of these en route tomarket. Although the process of my invention is not limited to thetreatment of White Rose potatoes, this is the main variety grown inSouthern and Central California, and the invention will therefore bedescribed for illustrative purposes as applied to this variety.

Potato producers have for long .been conscious of the effect which theappearance of potatoes have on the'prices they bring, but hitherto havedone little more along this line than to wash the potatoes to remove thesoil of the field. A considerable portion of the California. potato cropis harvested when only partially matured, because early potatoes bringhigher prices and because heat and tuber moth may cause injuyifthecropis allowed to grow until the vines die. Since the skin of immaturepotatoes is very thin, it is washing the unattractive appearanceproduced thereby, the severe discoloration of tubers has resulted in lowmarket prices. i

It is another object of my invention to provide It is a still furtherobject of my invention to provide a process for treating potatoes whichwill the transmission of infecto another in the washing process Withoutinducing the discoloration of the skinned areas above referred to.

The method of my invention embraces essentially the application of twoagents to the potatoes ing agent. Its action isordinarily accompanied byoxidation. The agent applied in the second treatment of my process is areducing agent or deoxidizer.

The agent employed in the rst treatment oi my process which may beadapted to'serve primarily as a detergent or as a fungicide `or as ableaching agent, also acts through oxidation to increase the rate ofenzymatic discoloration of those areas of the surfaces of the potatoeswhich are e posed to atmospheric oxygen following the treatment. I Thereducing agent applied inthe second treatment ofmy process does not undothe good work of the rst agenti but complements this by undoing itsdetrimental effects.y In particular the' reducing agent reverses theoxidation of the exposed lphelloderm in the skinned areas on thepotatoes which has been caused by the-agent of the flr'st treatment andpractically restores the condition of this phelloderm to what it wasprior to the application of the iirsty agent.

I have also found that the reducing agent ap# plied in the secondtreatment .oi my process not only reverses the detrimental action of therst agent Without interfering with the benecial results of itsapplication, but the second agent enhances the good effects of the firsting to brighten the unskinned areas o the pota-jA toes which have beenyellowe by the pplication of the first agent thereto an leaves thesewith a much more natural appearance and without reversing the bleachingreaction The agent which I prefer touse in the first step l oi' themethod of my invention is a hypochlorite of By alkali-forming anAalkali-forming metal.

metal, I mean those metals (like sodium and calcium) the oxides andhydroxides of which are using a solution 30 seconds or `my process maybe selected from a group commonly referred to as alkaliesl Of these hy--pochlorites I prefer to use vsodium hypochlorite. While the strength ofthis may vary, depending upon the length of the treatment and theobjects to be achieved, I nd that where bleaching and disinfection arethe primary ends in view, good results are produced on White Rosepotatoes by of sodium hypochlorite containing-2% of available 'chlorinefor a treatment of a 1% available chlorine solution for a treatment ofone minute. v An agent suitable for use in the second step oi asfollows: sulphites, bsulphltes, metabisulphites and thiosulphates ofalkali forming metals. I have found sodium bisulphite especiallysuitable for use as this agent. The desired reaction in the secage t bytendof the ilrstV agent.' 5

' treatmentsvof my proc in this second treatment over Fig. 2 is alongitudinal sectional view taken on I the line 2--2 of Fig. 1.

agent solution dry on the potatoes. The values given are merelyillustrative, of course, as considerable variation in the choice ofagents, the

concentrations used and the periods of treatment are allowable withoutsubstantial loss of the benents of the treatment. The group of reducingagents vabove named as suitable for use in the second step of myprocess, may also be correctly 1.,

designated as sulphur-containing antichlors.

As whatever quantity of hypochlorite remaining on the potatoes after theflrst treatment absorbs a chemical equivalent of the reducing agentapplied in the second treatment, it is desirable that the -potatoes berinsed between the two treatments to remove as much of the hypochloriteas possible, A reducing agent such as sodium blsulphite which is allowedto remain on the potatoes at the conclusion of the process, tends toretard enzymatic oxidation of the skinned areas and their consequentdiscoloration while the-ptatoes are on their wayto market. The 'residueof this agent also actsto protect the potato against reinoculation .by.spoilage organisms.

The agents in'each of the treatments of my process may be applied.either by soaking the potatoesin a solution vof Ythe agent or byflooding the solution over the potatoes.y equally satisfactory resultsmay be obtained by these ytwo, modes of. application, but for purposesof controlof the process I prefer to use the flood application in'bothtreatments.

I have found l Fig. 3 is an enlarged fragmentary sectional view taken onthe line 3-3 of Fig. 2, and illustrating the flooding of the solution onthe pctatoes in the primary treatment of my process.

Fig, 4 is an enlarged fragmentary cross sectional view taken on the line4-4 of Fig. 2, and illustrates the rinsing of the solution of theprimaryv treatment from the potatoes by spraying rinse water thereon.

Fig. 5 is an enlarged detail sectional view taken on the `line 5-5 ofFig. 3 and illustrating the manner in which the potatoes are supportedon the conveyors of the apparatus.

. c Referring specifically to the drawings, an apparatus I0 is showntherein for performing the process of my invention, this apparatusincluding a primary treatment and rinse unit II and a secondarytreat-ment unit I2.

The unit II includes a frame I5 having side ,walls I6 between which ismounted an endless vconveyor Ilhaving an endless series of rolls I8which are preferably provided with a chemically inactive coveringrISs'uch as of rubber or a'suitable'inertsynth'etic material. 'Theconveyor I1 includes a primary'treatment section 20 and' a rinse section2 Ij; Disposed beneath the upper run of the conveyor -I'I in the primarytreating section 20 is a-drain pan 22, fromwhich a pipe 23 leads to aprimary treating solution tank 24 containing a primary treating solutionB. Connected to the bottom of the tank 24 and drawing solution Btherefrom through a. pipe 25 is a motor- "driven pump 26 whichdischarges this solution through a pipe'21 and a manifold 28 into aseries 1 of flooding troughs 29 disposed transversely over TheV processof myinventionis preferably per-` formed continuously on a stream ofpotatoes conveyed through various pieces of equipment disposed inseries. Thus Athe potatoes may pass consecutively through a. potatowasher, a me-` chanical sizer. through the apparatus performing themethod of my invention,`and finally over a grading table from` which thepotatoes are sacked.

speomo formulas :ofthe solutions in the two which I have found to giveespecially good results in treating White Rose potatoes inCaliforniafareas follows'.

Primary solution .s i s by weight -Sodiumhypochlorite expressed asavailable chlorinev 1.0 Water and inert salts; 99.0

' met Secondary solution sodium' bisuiphite 25 Water 99.75 100.00

The process of my invetion` is, of course, in-

` v tended to be performed with apparatus which in the packing shedVsystem above outlined would Per cent receive the potatoes from thepre-washer or sizer and after processing these with the process of myinvention would deliver the potatoes to the grading table.

In the accompanyig drawings:

Fig. l is a plan .viewof an apparatus suitable for performing theprocess of my invention.

the primary treatment section 20 of the conveyor. Mounted above thetank-241s a concentrate reservoir 35 having a valve 38 through whichconcentrate from the reservoir 35 may be allowed to trickle into the-body of the solution 'B'contained in the tank 24 to maintain theconcovering material aforesaidfto retain the potatoes on the conveyorand prevent/the solution having direct access to the conveyors ins.

Positioned at the receiving end of the unit II is a drop board 45 overwhich the potatoes are adapted to be delivered, as from a sizer (notshown) onto the conveyor I1.

Disposeda beneath the upper run of the conveyor I 1 and the rinsingsection 2l of the unit II is a drain pan 46 from which a pipe 'lconnects with the'sewer. Extending transversely across the unit II abovethe conveyor Il in the rinsing section 2| is a fresh Water rinse pipe 48having a series of spray nozzles 49 from which Vwater is adapted to besprayed downwardly as shown'ln Fig. 4, on potatoes carried on the cori-4veyor I1 through this section. Fresh rinse water is delivered to thepipe 48 through a valved pipe 50 connecting with the domestic watersystem to produce sprays 5 I Unit I2 is placed slightly below the unit Iand in position to receive the potatoes discharged from the latter overa drop board BD. The u'nit I2 includes a frame BI having side walls d2between which is mounted an endless conveyor 63 contains a. secondarytreating solution R. Con` nected to the bottom of the tank 61 anddrawing solution therefrom through a pipe 68 is a motordriven pump -69which discharges this 'solution into a pipe through which it isconducted to a flood trough 1l mounted transversely across the unit l2above the pan 65. The trough 1| is similar in construction to thetroughs '29 described hereinabove., y

Mounted above the tank 61 is a. concentrate reservoir having a valve 16through which concentrate from the reservoir 15 may be allowed totrickle into the body of solution R contained in the tank 61 to maintainthe concentration oi this substantially constant.

Potatoes are discharged from the conveyor 63 over a drop board 80 onto-a grading table 6l having a horizontal 'conveyor ybelt l82 forconveying-the potatoes away from the apparatus l0.

Suitable power means (not shown) is provided for driving the conveyorsl1, 63 and 82, and for operating the pumps 26 and 69.

Before commencing commercial'practice of the method of my invention withthe apparatus I6, tanks 24 and 61 are ,charged with primary andsecondary treating solutions B and R and the reservoirs 35 and 15 arecharged with'quantities of concentrates and the valves 36 and 16 turnedon to permit trickling of the concentrates into the respective solutionsto maintain the strength of the latter within suitable operating limits.

The operation of the pump 26 now causes a circulation of the solution Bvby withdrawing the solution from the bottom of the tank, flooding' itover the upper run of the conveyor l1, this solution then iiowingthrough the -conveyor and returning through the pipe 23 to the tank 24.Likewise the operation of thev pump 69 causes circulation of thesecondary treating solution R, by withdrawing it from the bottom of thetank 61, iiooding it over the upper run of the conveyor 63, thissolution then flowing through the conveyor 63 and returning by the pipe.66 to the tank 61.

The apparatus I0 is now in readiness to receive a. iioW of White Rosepotatoes from a washer and sizer preceding the same when this flowstarts coming over the drop board 45. The apparatus l0 is preferablyoperated at such a speed relative to the processing devices deliveringpotatoes thereto so that these potatoes pile up in layers two orthree-deep as shown in Fig. 2. When the preferable conditionsaforestated are being followed in the performance of the method of myinvention, the solution B is an aqueous solution of sodium hypochloritecontaining 1% available chlorine with a concentrate ofthe same agentbeing fed" thereto from the reservoir 35. The solution R in the tank 61under these preferred conditions is an aqueous solution of 1% by weightof sodium bisulphite and the reservoir 15 contains a concentrate of thesame agent. The valves 36 and 16 remain open 'during the operation ofthe process to maintain the strength tions B and R substantiallyconstant.

When the apparatus I6 is in operation the conveyors l1 and 63 travel atthe same rate, which is such as' to subject the potatoes to the of thesoluaction of solution B while these potatoesare travelling through theprimary treating section 26,'for the desired length of time fortreatment with the primary solution. Under the preferred conditionsoutlinedthis period would be approximately one minute.

The primary solution B is now rinsed from the potatoes bythe rinsesprays 6l. As the secondary treatingsolution R is allowed to remain .onthe potatoes after this is flooded over these in the .treating unit l2,there is,I no particular need oi a longer treatment of the potatoes withthe solution R than that afforded by the single flooding trough 1l. Thisvgives the potatoes continuous flooding contact with the fresh solutionR for a period of about five seconds and a considerably longer contactwith this solution while the latter is drying onthepotatoes. After thisflooding of solution R on the potatoes is nished, they proceed'to theend oi the conveyor 63 and'gravitate from this over the drop board 80onto the conveyor 82 of the grading table 8l alongside which soz-tersstand and grade the potatoes, after which the potatoes are immediatelysackedV and loaded aboard cars for shipment.

The treatment of White Rose potatoes inthe specic example vof my processabove described produces an attractive light color in the skin of thesepotatoes which is not present in the potatoes prior to treatment. Theimprovement `in appearance is especially noticeable in thosepotatoes-which have rough. unattractive skins s ned areas and alsoimparts a yellowishness to the unskinned areas which it bleaches. Theseundesirable results of the hypochlorite treatment are overcome by thesubsequent treatment with a reducing agent so that only the beneficialeffects of the hypochlorite remain after'the potatoes have passedthrough the entire process., The yellowing of the unskinned portions ofthe potato produced by the hypochlorite is believed toy be ydueto thealkalinity of the latter and the elimination of this yellowing by thesecondary solu- K result from the neutralization tion is believed to ofthe alkalinity of the yellowed areas.

While the decay in potatoes shipped from California to the easternmarkets seldom exceeds 2%, a substantial degree oi control of this decayis effected by the process of my invention by the sterilizing action ofthe hypoohloriteon the decay organisms with which the potatoes may havesolution of a hypochlorite of an alkali-forming been infected in thewasher. f

What I claim is:

1. A method of treating potatoes which comprises: contacting thepotatoeswith an aqueous solution of a. hypochlorlte of an alkali-i'ori'ningmetal, and subsequently contacting said with an aqueous solutioncontaining a reducing agent selected from a group consisting ofphosphites, sulphites, bisulphites, metabisulphites and thiosulphates ofalkali-forming metals.

2. A method of treating potatoes which comprises: contacting thepotatoes with an aqueous solution of a -hypochlorite of analkali-forming metal, rinsing said solution from the potatoes andsubsequently contacting said potatoes with an aqueous ysolutioncontaining a reducing agent selected from a group consisting ofphosphites, sulphites, bisulphites, metabisulphites and thiou potatoessulphates of alkali-forming metals.

3. A method of treating potatoes which comprises: contacting saidpotatoes with an aqueous contacting said potatoes with an aqueoussolution of sodium bisulphite.

5. A method of .treating potatoes which comprises: contacting saidpotatoes with an aqueous solution of sodium hypochlorite, rinsing saidpotatoes, and thereafter contacting said potatoes with an aqueoussolution containing a reducing agent.

6. A method of treating potatoes which comprises: contacting potatoeswith a solution of hypochlorite with a strength of at least 1% availablechlorine for a period of atleast one minute, rinsing said solution fromsaid potatoes and contactingsaid potatoes with an aqueous solution of areducing agent.

7. A method of'treating potatoes which comprises: contacting potatoeswith a. solution of hypochlorite with the strength of at least 1%available chlorine for a period of at least one minute, rinsing saidsolution from said potatoes and contacting said potatoes with an aqueoussolution containing a reducing agent selected from a group consisting ofphosphites, sulphites.

, with an aqueous solution containing a reducing agent selected from agroup consisting of phosphites, suiphites, bisulphites, metabisulphitesand thiosulphates of alkali-forming metals, and per mitting saidsolution of reducing agent to remain on said potatoes.

9. A method of treating potatoes which compriseseontacting said potatoeswith an aqueous solution of a hypochlorite of an alkali-forming metal,and thereafter contacting said potatoes with an aqueous solution of anantichlor.

10. A method of treating potatoes which comprises contacting saidpotatoes with an aqueous solution of a hypochlorite of an alkali-formingmetal, and thereafter contacting said potatoes with an aqueous solutionof a sulphur-containing antichlor.

ARTHUR. F. KALMAR.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Sharma May 28, 1935

